BIO 1201 EXAM 3 LSU

True or False: The purpose of mitosis is to insure that daughter cells have identical genetic information at the mother cell.

true

How many centromeres are there per chromosome?

1

How many centrosomes per chromosome consist of 2 sister chromatids?

1

When is DNA replicated?

S phase

When are sister chromatids separated?

Anaphase I

If the DNA content in G2 is X, what is the DNA content of each daughter cell at Telophase?

0.5X

If the DNA content in G1 is X, what is the DNA content of each of the daughter cells at Telophase?

X

DNA replication checkpoint occurs where?

G2

We inherit our mitochondria from our...

our mother

In mitosis when do homologous chromosome pairs separate?

in mitosis, homologous chromosomes do not separate

In meiosis when do homologous chromosome pairs separate?

Anaphase I

At G2, the amount of DNA is X. At Telophase II the amount of DNA in each of the daughter cells is...

0.25X

At G1, the amount of DNA is X. At Telophase II the amount of DNA in each of the daughter cells is...

0.5X

At G2 there are 40 chromatids, what is the diploid chromosome number?

20

At G2 there are 40 chromatids, at Telophase II each daughter cells has how many chromosomes?

10

At G2, there are 40 centrosomes, at Telophase II each daughter cell has how many chromosomes?

20

Why don't we talk about Gossian genetics?

he was not quantitative with his work

What is the alternative form of a gene?

allele

How many different alleles can a diploid individual have at a single gene locus if there are 4 alleles in the population?

2 alleles

True or False: Recessive alleles are not expressed because they code for an inactive or defective enzyme.

true

What is an example of a genotype?

PP, Pp, or pp

In genetics, what determines what?

genotype determines phenotype

An individual with 2 Barr Bodies has how many chromosomes?

3: 2 are inactive, 1 is active

X chromosome inactivation happens how?

random and all but one

Calico and tortoiseshell cats are examples of...

X chromosome inactivation

Could an Rh+ man be the father of an Rh- child?

yes

If both parents are carriers for sickle cell anemia, what is the percent of their children that will have the disease?

25%

Why is the sickle allele maintained in populations, particularly in Africa and the Mediterranean Sea area?

Heterozygotes are immune to Malaria

Does testing newborns for diseases save money?

yes

How much does it cost to test your child in the state of LA?

$30

True or False: In an autosomal recessive trait, if two affected individuals have offspring then all of their children will have the trait.

true

True or False: In mitosis it does not matter if you have unpaired chromosomes.

true

How many barr bodies are there in the nucleus of a Turner's female cell?

0

Turner's female, XO, 45 is n example of...

aneuploidy

How many barr bodies in the preceding Klinefelters male (XXXXY)?

3

A Klinefelters male, XXY 47, is an example of...

aneuploidy

True or False: XXX females are usually normal because the other 2 X's are inactivated.

true

An XXX female has how many barr bodies?

2

What do males inherit from their mothers?

X chromosomes and mitochondria

True or False: Initially protein was thought to be genetic material because it was thought to be more complex than nucleic acids.

true

Which takes more energy to break?

G-C, 3 hydrogen bonds

True or False: A double strand of DNA has a uniform width.

True

DNA replication is...

semi-conservative

The 5' end of the DNA strand has a...

phosphate group

The 3' end of the DNA strand has a...

hydroxyl group

Human DNA does not incorporate AZT. Why?

human DNA polymerase has a proof-reading ability

True or False: The double helix is antiparallel this refers to the directionality of the strands.

true

The base pairing between strands is stabilized by...

hydrogen bonds

"A" pairs with what base?

T

The enzyme that inserts the RNA primer in DNA synthesis is...

primase

DNA polymerase works 5' to 3'?

adds to the 3' hydroxyl group

True or False: Both the leading and lagging strands are synthesized 5' to 3'.

true

What enzyme stiches together Okazaki fragments?

ligase

True or False: New monomers are added to the free 5' phosphate in the growing DNA chain.

false

True or False: The central dogma has no exceptions.

false

The anti-codon base pairs to the mRNA are...

anti-parallel

DNA template: 5' ATGC 3', RNA made:

3'UACG5'

The central dogma does what?

DNA is transcribed into mRNA which is translated into proteins

What transfers the genetic message from the nucleus to the cytoplasm?

messenger RNA

In contrast to DNA, RNA has a

2' OH group

RNA base not found in DNA...

uracil

What is the expressed part of the pre-mRNA?

exon

True or False: "Expressed part" means the sequence that is translated into protein.

true

tRNA is

an adapter molecule recognizing an amino acid and a codon

The anticodon and codon base pair are...

anti-parallel

True or False: Introns are removed for prokaryotic mRNA.

false; processing an mRNA only occurs in eukaryotes

What is translation?

synthesis of protein

Features of tRNA

anti-codon, amino acid binding cite, at least one tRNA for each amino acid

Which is the first tRNA to come onto the ribosomes for polypeptide synthesis?

MET-tRNA; this protein starts translation

What is a mutation?

change in DNA

If a somatic cell is just about to divide, it has ___ chromatids.

92

You would know a dividing cell was a plant cell rather than an animal cell if you saw that _____.

it had formed a cell plate

The centromere is a region in which _____.

sister chromatids are attached to one another in prophase

At which point in the cell cycle do centrosomes begin to move apart to two poles of the cell in a dividing human skin cell?

prophase

Sister chromatids _____.

have matching copies of the chromosome's DNA, are created when DNA is replicated, are attached at the centromere prior to division, are separated during mitosis

A biochemist measured the amount of DNA in cells growing in the laboratory and found that the quantity of DNA in the cells doubled _____.

between the G1 and G2 phases

A cell entering the cell cycle with 32 chromosomes will produce two daughter cells, each with _____.

32 chromosomes

If a cell contains 60 chromatids at the start of mitosis, how many chromosomes will be found in each daughter cell at the completion of the cell cycle?

30

A cell biologist carefully measured the quantity of DNA in grasshopper cells growing in cell culture. Cells examined during the G2 phase of the cell cycle contained 200 units of DNA. What would be the amount of DNA at G1 of the cell cycle in one of the grasshopper daughter cells?

100 units

During anaphase of mitosis _____.

the centromeres divide, a spindle made of microtubules is present, the centrioles are at opposite poles, identical chromatids move to opposite poles

A human somatic cell contains _____.

44 autosomes, 2 sex chromosomes

What is the function of meiosis?

to make cells with haploid (half that of the parents) number of chromosomes

One difference between meiosis I and meiosis II is that _____.

crossing over occurs in meiosis I, but not in meiosis II

If there are 20 chromatids in a cell in G2, how many centromeres are there?

10

In sexually reproducing species, the chromosome number remains stable over time because _____ and _____ always alternate.

two diploid cells ... four haploid cells

Humans have 46 chromosomes. That number of (human) chromosomes will be found in _____.

liver cells

In a diploid cell containing 10 chromosomes, meiosis results in the formation of daughter cells containing _____ chromosomes.

5

Which one of the following occurs in meiosis, but not mitosis?

homologous chromosomes separate

Crossing over is _____.

the exchange of homologous portions of non-sister chromatids

Which of the following is (are) true for alleles?

They can be identical or different for any given gene in a somatic cell. They can be dominant or recessive. They can represent alternative forms of a gene.

All the offspring of a cross between a black-eyed MendAlien and an orange-eyed MendAlien have black eyes. This means that the allele for black eyes is ________ the allele for orange eyes.

dominant to

A plant with purple flowers is allowed to self-pollinate. Generation after generation, it produces purple flowers. This is an example of

true-breeding

Pea plants were particularly well suited for use in Mendel's breeding experiments for all of the following reasons except that

peas have an unusually long generation time

A cross between homozygous purple-flowered and homozygous white-flowered pea plants results in offspring with purple flowers. This demonstrates

dominance

In cattle, roan coat color (mixed red and white hairs) occurs in the heterozygous (Rr) offspring of red (RR) and white (rr) homozygotes. Which of the following crosses would produce offspring in the ratio of 1 red:2 roan:1 white?

roan x roan

What is the expected phenotypic ratio of a cross between two orange-eyed MendAliens?

0 black-eyed: 1 orange-eyed

All the offspring of a cross between a red-flowered plant and a white-flowered plant have pink flowers. This means that the allele for red flowers is ________ to the allele for white flowers.

incomplete dominant

A genetic defect in humans results in the absence of sweat glands in the skin. Some men have this defect all over their bodies, but in women it is usually expressed in a peculiar way: A woman with this defect typically has small patches of skin with sweat glands and other patches without sweat glands. In women, the pattern of sweat-gland distribution can best be explained by _____.

X chromosome inactivation

A person with two X chromosomes and one Y chromosome would appear to be _____.

male

Hemophilia is a sex-linked disorder. The daughter of a father with hemophilia and a carrier mother has a _____ probability of having hemophilia.

50%